1. Field of the Invention
The present invention relates to a process of mixed analogue and digital radiobroadcasting making it possible to ensure the transition between conventional amplitude-modulation radiobroadcasting systems, for example, and digital radiobroadcasting systems. It applies in particular to the production of a transmitter broadcasting in the short-wave range.
2. Discussion of the Background
For reasons of a technical, political or economic nature, radiobroadcasting transmitters currently used for the radiobroadcasting of programs using amplitude modulation cannot be adapted overnight to the broadcasting of programs in digital form. This suggests, for a relatively long transition period, the coexistence of two systems, one digital the other analogue, which broadcast the same programs. This solution would appear to be very expensive and rather undesirable since it implies that, at the end of this transition period, half the transmitters used for analogue transmission will have to be discarded.
The purpose of the invention is to remedy this situation.
To this end, the subject of the invention is a process of mixed analogue and digital radiobroadcasting of a radiophonic transmission broadcast by one and the same transmitter and intended to be received either by amplitude-modulation receivers or single-sideband receivers and digital type receivers adapted for the demodulation of multi-subcarriers, characterized in that it consists in transmitting a composite signal whose frequency spectrum is composed of a first analog spectrum representative of the amplitude modulation or of the single sideband and of a second spectrum composed of the multi-subcarriers, the first and second spectra occupying two disjoint frequency bands.
Its subject is also a device for implementing the aforesaid process.
The advantage of the invention is that it allows simultaneous analog and digital radiobroadcasting by one and the same transmitter of a transmission which can be received equally well by an amplitude-modulation receiver available on the market without it being necessary to modify it or change it, as by a receiver fitted with a digital signal demodulator.